The present invention relates to an endoluminal prosthesis to be deployed at a vessel bifurcation, comprising a one-piece graft sleeve, said graft sleeve having a branching portion, defining a first prosthesis lumen, said branching portion having, in its deployed state, a first diameter and being reinforced by stent elements, and a trunk portion, defining a second prosthesis lumen in fluid communication with said first prosthesis lumen, said trunk portion having, in its deployed state, a second diameter.
Further, the present invention concerns a catheter having loaded thereon such an endoluminal prosthesis and configured for placing said endoluminal prosthesis at a vessel bifurcation, said catheter comprising a catheter body, having a guide wire lumen, for accommodating a guide wire, and a graft actuator lumen, a constraining sheath, for keeping radially compressed therein said loaded endoluminal prosthesis, and a graft actuator, accommodated in said graft actuator lumen.
Still further, the present invention relates to a deployment system, comprising such a catheter and such an endoluminal prosthesis, loaded onto said catheter.
Even further, the present invention relates to a method for deploying such an endoluminal prosthesis at a vessel bifurcation, using such a deployment system, the method comprising the steps of                a) introducing via a first branching vessel said deployment system into a vessel bifurcation,        b) opening or retracting the first constraining sheath in order to release the endoluminal prosthesis, and        c) advancing a trunk portion into a vessel of the vessel bifurcation.        
Such an endoluminal prosthesis, catheter, deployment system and method are known for example from WO 00/053251 A1.
Endoluminal prostheses, catheters and deployment systems of the kind mentioned at the outset are of high medical relevance and commercial impact, being, in many cases, the prime treatment for aneurisms like the abdominal aortic aneurism.
An aneurism is a localized dilation of a blood vessel wall usually caused by degeneration of the vessel wall, for example caused by artherosclerosis. In such cases, the dilation of the blood vessel may ultimately result in a rupture of the vessel wall, causing severe hemorrhage.
Aneurisms most frequently occur in the aortic system, whereby abdominal aortic aneurisms, for example at the aortic and iliac bifurcation, are particularly life-threatening. An estimated 65% of patients suffering from the rupture of such aneurisms die from sudden cardiovascular collapse before arriving at the hospital. This is owing to the fact that large volumes of blood are constantly transported along the abdominal aorta, the rupture leading to instant and extensive blood loss into the surrounding body cavities and tissues.
Methods of treatment of aortic aneurisms exist for several decades. In these methods, usually, a fully artificial replacement, for example a stent-graft or a xenograft, is used to replace or exclude from the blood flow the part of the vessel featuring the aneurism. Such bifurcation grafts, which can be utilized for treating aneurisms at the aortic and iliac bifurcation, are known for example from U.S. Pat. No. 2,845,959. However, such devices have to be placed in open surgery, inflicting a high degree of trauma on the often already otherwise health-compromised patient.
During the past years, the development of surgical treatments has gradually concentrated on endoscopic techniques, which allow the treatment of for example the vessel system in a manner avoiding the larger part of the traumata associated with open surgery. In this connection, self-expanding or balloon-dilated stents and stent grafts have become increasingly relevant.
For deployment, the circumferentially compacted endoluminal prosthesis (i.e. the stent or stent graft) is advanced, using a catheter, through a blood-vessel towards the site of, for example, the aneurism, and is than inflated, thereby becoming anchored to the healthy vessel-walls proximal and distal to the site of the aneurism. The lumen of the prosthesis at this point replaces the lumen of the vessel, excluding the aneurismic lumen from the blood flow.
In the case of the placement of an endoluminal prosthesis at branched vessels, typically, several catheters are introduced into the vessel system from different access-points. The branching vessels are then supported by different endoluminal prostheses, connected to each other by frictional force or other mechanical connections.
The problem here is that the connections between different endoluminal prostheses are to some degree prone for developing endoleaks or even for complete disconnection, when subjected to the forces occurring during the remolding process of the aneurismic dilation or when subjected to the natural movements taking place inside the human body. In such cases, the protective function of the endoluminal prosthesis is heavily compromised, potentially entailing thrombus formation or vessel rupture.
In order to avoid such leakage problems, WO 00/053251 A1, mentioned at the outset, describes an endoluminal prosthesis with a one-piece graft, which endoluminal prosthesis is adjusted for the placement in the aortic and iliac bifurcation. Further, WO 00/053251 A1 describes a deployment system adapted for the placement of this endoluminal prosthesis.
This deployment system is adjusted for a single access deployment, necessitating only one surgical entry point into the vessel system.
For this purpose, the deployment system comprises a catheter with a catheter body and a constraining sheath, the endoluminal prosthesis being comprised in between the constraining sheath and the catheter body. The endoluminal prosthesis features a main tubular body, comprising a trunk portion to rest in the aorta, and a branching portion to rest in the ipsilateral iliac artery, and a side branch that is to rest in the contralateral iliac artery, which side branch, in its undeployed state, is folded to the side of the main tubular body.
After the known prosthesis has been introduced into the aortic and iliac bifurcation via the ipsilateral iliac artery, the endoluminal prosthesis is partially released by shifting the constraining sheath in longitudinal direction. The side branch of the endoluminal prosthesis is then inserted into the contralateral iliac artery by retracting the entire endoluminal prosthesis and the prosthesis is fully deployed. According to WO 00/053251 A1, the main tubular body of the endoluminal prosthesis extends in the ipsilateral iliac artery as well as in the aorta and is reinforced by stent elements. Similarly, the side branch, coming to rest in the contralateral iliac artery, is reinforced by shape memory stent material.
This principle, however, bears important disadvantages.
According to some embodiments of the endoluminal prosthesis according to WO 00/053251 A1, there exists a considerable difference in the geometry and structure of the stent elements reinforcing the branching portion of the main tubular body, resting inside the ipsilateral iliac artery, and stent elements reinforcing the side branch in the contralateral iliac artery.
This difference leads to differences in the circumferential rigidity of the parts of the endoluminal prosthesis. Such differences in circumferential rigidity however may lead to long-term difficulties such as migration and mechanical dislocation of either the branching portion of the main tubular body or the side branch. In this case, the probability of endoleaks, forming between the distal ends of the prosthesis and the vessel wall, is increased.
In the remaining embodiments of the endoluminal prosthesis according to WO 00/053251 A1, the deployment mechanism itself is mechanically highly complex and, therefore, is prone for defects and incorrect or incomplete deployment. Such incorrect or incomplete deployment may result in the complete failure of the operation, making necessary open surgery, or may at least aggravate the risk for the formation of endoleaks.
Moreover, at least one of the vessel branches downstream of the vessel bifurcation is completely obstructed for a certain amount of time during the process of deployment.
In case of mechanical failure of the complex deployment mechanism, this vessel will even remain blocked, until the entire deployment system is removed in open surgery.
Especially in case of larger vessels, this obstruction may put at risk the patient's health.
Furthermore, the system according to WO 00/053251 A1 is, owing to its mechanical complexity, expensive in manufacture.